Artists Heike Mutter and Ulrich Genth created an artwork that looks like a massive roller coaster. But instead of a fast-moving thrill ride, it’s a curved sculpture made up of hundreds of carefully crafted steps that people walk on. The structure sits on a hill in Duisburg, Germany.

The artists named the sculpture Tiger & Turtle—Magic Mountain. The project took two years and 120 tons of steel to build. To make the work safe for visitors, the artists had to carefully consider the angle of each stair.

Since it opened in 2011, Tiger & Turtle—Magic Mountain has become a popular sightseeing spot. “Roller coasters usually last about 30 seconds,” one visitor says, “but this one took me 45 minutes.”